In recent years, digital cameras have increased in popularity, both as stand-alone products and as part of other devices such as cellular telephones, personal digital assistants and other devices.
In both stand-alone digital cameras and cameras that are incorporated into devices such as mobile telephones, a viewfinder is often used to view an image before the image is actually captured by the camera module. Individuals may use the viewfinder to ensure that they have correctly framed the image, that the picture will not be tilted, and that the image is in proper focus. The viewfinder can take the form of a small LCD screen, which can also be used to perform other functions when the camera is not being used.
Although a viewfinder usually provides a user with a larger area to view the subject of the photograph than traditional camera viewing windows, they are still usually relatively small in size. For example, on a mobile telephone with digital camera capabilities, the viewfinder is no wider than the width of the mobile telephone. This small size makes it relatively difficult to see fine details on the viewfinder, and it also makes it difficult to determine whether objects or regions of the image are in proper focus. In addition, the relatively high processing capabilities that are required for a mobile device to display an image in substantially real time can also affect the appearance of such an image on the viewfinder. For these reasons, it can be quite difficult for a user to determine whether the level of focus in an image is of an acceptable quality.
Conventional systems have attempted to address this issue with various systems, but each has a number of drawbacks. For example, one conventional system automatically changes the color of the viewfinder's focus frame when the focus has been locked at an acceptable level. However, until the focus is locked, the user is not provided any information as to whether the image or individual portions are close to being in-focus and, if so, how close to being in focus. Other systems superimpose rectangles on those portions of the image that are most likely in focus. However, such systems do not provide sufficient information to the user about the relative level of focus for individual portions of the image.
It would therefore be desirable to have a system where a user is provided information concerning the level of focus of various objects or regions within an image as it is being shown on a viewfinder.